Gnosticism is generally believed to have emerged in the early centuries of the Common Era, around the 1st to 2nd century AD, although its roots may trace back to earlier philosophical and religious traditions. It is characterized by its diverse beliefs and emphasis on personal spiritual knowledge (gnosis) over orthodox teachings. Gnosticism flourished alongside early Christianity but was eventually deemed heretical by mainstream Christian authorities.
Gnosticism can be read about in many books. The Gnostic Society has their own Library in which everything about the Gnosticism can be learned or studied.
there is no scientific basis for Gnosticism or orthodox (mainstream) Christianity.
Simon Magus
Pneuma
No book in the bible addresses Gnosticism, you are looking for Against Heresies as written by a father of the church, Irenaeus.
The opponents of Gnosticism were primarily early Christian leaders and theologians, such as Irenaeus and Tertullian. They argued against Gnosticism's belief in secret knowledge and its rejection of the material world, emphasizing instead the importance of orthodox Christian doctrine and the belief in a loving creator God.
Test
Deirdre Joy Good has written: 'Reconstructing the tradition of Sophia in Gnostic literature' -- subject(s): Gnosticism, Wisdom (Gnosticism) 'Mariam, The Magdalen, And The Mother'
Daniel L. Hoffman has written: 'The status of women and Gnosticism in Irenaeus and Tertullian' -- subject(s): Women in Christianity, Gnosticism, Social conditions, History, Women
Mary Ann Donovan has written: 'Irenaeus' teaching on the unity of God, and his immediacy to the material world, in relation to Valentinian Gnosticism' -- subject(s): Gnosticism, Valentinians
Ithamar Gruenwald has written: 'Messiah & Christos' 'From apocalypticism to Gnosticism' -- subject(s): Apocalyptic literature, Gnosticism, History and criticism, Judaism, Merkava in rabbinical literature, Mysticism
The common belief is that Gnosticism originated as a branch of Christianity. There are some theories that claim the central ideas of Gnosticism existed before the birth of Christ. These ideas, of a dualistic religion (two Gods), still prevail today in modern Christianity with the teachings of one supremely good God of Heaven and one sinful, loathsome God of Hell.